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  • Shaper cut gears

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    [This message has been edited by John Stevenson (edited 01-08-2006).]
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    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.




  • #2
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    • #3
      John, I did some thinking on this and I've concluded to a certainly one could make true involute spur and bevel gears on a shaper if he were dedicated. He could also make helical gears.

      The problem isn't theory but working out the details and appling them.

      I try to find some links.

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      • #4
        John,
        Here is one Gear Cutting Group that might offer some insite:
        http://groups.yahoo.com/group/mwmills2/
        Also, this Metal Shapers Group has had postings on cutting gears:
        http://groups.yahoo.com/group/Metal_Shapers/messages/
        Good luck,
        Jim Larsen

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        • #5
          John,
          Here are a few other URL's that are helpful in gear cutting:
          http://www.communitypc.com/
          This Meshing with Gears Discussion Forum is part of the above and is full of great info:
          http://www.communitypc.com/wwwboard/wwwboard.html
          Good luck,
          Jim Larsen

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          • #6
            Jim,
            Many thanks for the links. I did know about the last three and visit them but the first one is new to me.

            John S.
            .

            Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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            • #7
              John
              Okay lets get it over---I am green with envy--after having a 7inch shaper for all summer, I would like a bigger one. The one you bought looks like a real gem.
              So if 1) you ground a tool shaped like the tooth of a rack 2) you decided what the pitch distance of the rack was 3) you traversed the gear at the correct pitch spacing, taking several depth cuts at each space 4) indexed the gear one tooth and repeated step 3. Would you create the correct shaped gear tooth for the particuliar tooth count?
              I guess I will try to use my CAD system to model this idea.
              Pete

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              • #8
                John,
                Any chance you could scan the ME article? I would like to read that one if possible.
                It would be a good article to put in the YG files mentioned above.

                BTW, if you don't know, there is a list on the following home page

                http://groups.yahoo.com/group/mlprojects/

                of about 10 YG which are dedicated to running old ME articles. See each groups 'Files'. Note also, there are also "extra" groups not mentioned, eg mwhints2 and mwhints3

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                • #9
                  Ever see a cutter for a Fellows gear shaper?Its a disc with many involute teeth,but as I remeber its not tooth count specific like a common milling cutter,and they go for cheap on ebay,anyway my only experience with gear cutting on a shaper has been large rack gears,but form what I have heard and read in books it is possible to cut many different and perverted gears on a shaper.
                  I just need one more tool,just one!

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                  • #10
                    I found the thread on shaper cut gears I started on Practical Machinist 5/05/03. John made substantial contributions made the time.

                    http://www.practicalmachinist.com/ub...ML/001577.html

                    The idea has been around since the turn of the century. My take on the subject of cutting gears on a shaper is it's a good, practical, and accurate method but it's inherently slow for production.

                    If electronic indexing was coupled to a mechanical work piece roll/translation mechanism shaper cut true involute gears would be well within the capabilities of a home shop owner who's had to shy away too many times from the cost of soft steel gears from Martin or Boston Gear.

                    [This message has been edited by Forrest Addy (edited 10-13-2003).]

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                    • #11
                      Don't mean to steal the thread but I just cut two 48 DP , 20 deg P.A. gears for a model engine I'm building. I ground a 40 degree included angle lathe tool and made my own straight tooth (not helical) gear hob out of 01 and hardened it. I then set up the gear blank in one of those cheap indexing fixtures and the hob in the vertical mill. The hob has 5 teeth and the middle tooth must be lined up with the center of the gear blank. I then proceeded to cut the teeth one at a time. As one whole depth is being cut by the middle tooth, the cutting teeth above and below are also forming the gear teeth above and below. This continues all the way around the gear. It probably doesn't form a perfectly smooth involute tooth, but it is darned close and the resulting gears run pretty smooth. I first learned of this method in an article written in Strictly I.C. several years back.

                      Greg
                      "The truth is incontrovertible, malice may attack it, ignorance may deride it, but in the end; there it is." Winston Churchill

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                      • #12
                        Sunderland made BIG gear shapers.

                        They used a section of rack as a cutter, and rotated the gear as they reciprocated and moved the rack. The rack generated the profile as the tooth rotated into and out of mesh.

                        While fairly slow, I understand they made very accurate gears, and were not really that much slower than other methods for large size gears.

                        The rack was working on several teeth at a time. So, it was considerably faster than most any single cutter methods, and way cheaper than a hob method.

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                        • #13
                          .

                          [This message has been edited by John Stevenson (edited 01-08-2006).]
                          .

                          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                          Comment


                          • #14
                            Pretty much as I thunk it out but I don't have the electronic smarts to coordinate the step motor index with the roll.

                            Inherent resolution is important too. "Tenths" (microns) matter to gear tooth profiles. The index and the roll are simple math proportioning steps to index and translation to generate a true involute. I'd suggest a step rate and reduction gearing to give 100,000 steps per inch of roll and transation.

                            In these days of low cost servo motors (I have six three hundred watt motors with rotary encoders I bought off ebay) and Rutec or Gecko step and direction servo motor drives, US Digital feedback components, low cost step and direction drivers, only a bit of software development stands in the way of quality home brew gears.

                            Comment


                            • #15
                              I think they're using the rack to rotate the blank past the cutter, not cut the gear.

                              You have to already have a gear the same number of teeth to go this way.

                              How about a plate with a slot(on the indexing head) and stationary pin (mounted on the machine) to rotate the gear blank past the cutter.

                              Mount this plate on the back of a freely rotating head and put index holes on the blank somehow.

                              Have to set the pin at the proper pitch diameter in relation to the gear.

                              mite?

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